This paper studied the possibility of high-temperature storage of green mature tomato fruit. First, green mature tomato fruit were stored at 25, 31, 33, 35, and 37 0C for 17 days and thereafter shifted to 25 0C to check the effect of storage temperature on fruit freshness before and after shifting to 25 0C. In another experiment, tomato fruit were harvested at green mature stage and stored at 33 0C for 0 (control), 5, 10, 20 and 30 days, thereafter shifted to 25 0C to investigate the effect of high-temperature storage on fruit freshness before and after shifting to 25 0C. This research was conducted at Tokyo University of Agriculture, Japan from 2017-2019. Fruit color development, weight loss, fruit firmness, ethylene production, CO2 release, Brix, sugars, organic acids, 1-amino cyclopropane-1-carboxylic acid (ACC) content, and ACC oxidase (ACO) activities were measured as freshness indices. The possibility of longer storage of green mature tomato fruit under high temperature was discussed, which might well contribute to facilitate the harvesting operation in the summer season in developing countries, like Southeast Asian countries.